In the operation of a hard disk drive or a tape drive, the read head transducer flies over the magnetic data storage device. When increasing data density on the magnetic data storage device, transducer fly-height may be reduced as measured from the disk surface to the transducer tip. Reduction of the transducer fly-height may result greater effective sensitivity of the read head to the magnetic fields of magnetic domains on the magnetic data storage device. As fly-height is reduced and data density increases, the read head can experience read errors from unwanted, substantially random positioning error relative to a data track due to vibration, electrical noise, or the like. These types of position errors are referred to herein as track mis-registration (TMR) effects. Therefore, magnetic spacing measurement improvements may be used to reduce the mean fly-height and variation in fly-height of the read head over the magnetic data storage device. The variance in measurements due to TMR become more problematic as track pitch is reduced and TMR targets become more difficult to achieve. Such fly-height considerations also are important for write head spacing.